Tips to spot, treat and prevent fescue toxicosis
Fescue toxicosis, commonly known as fescue foot or lameness, is an uncommon, but very harmful disease occurring in livestock specifically in winter months. The disease is caused by toxins in tall fescue grasses.
Fescue toxicosis is often referred to as fescue foot, primarily because these toxins constrict blood vessels specifically at the extremities: ears, feet and tail. Ken Coffey, a University of Arkansas animal science professor, said if producers start to see a problem in their herd, remove them from the field as fast as possible because the disease is not reversible if it goes too far.
“There is no good way to avoid fescue toxicosis other than to replace toxic forage with non-toxic forage,” Coffey said. “Fall calving cows will not be affected as badly as spring calving cows because of winter breeding.”
Dr. Bridger Smithers of Smithers Animal Hospital said there are some indicators for the disease.
“Lameness is the first sign for a typical producer,” Smithers said. “Susceptibility of cattle is subject to individual variation. Low environmental temperature may exacerbate the lesions of fescue lameness; however, high temperatures increase the severity of a toxic problem known as epidemic hyperthermia or “summer syndrome,” in which a high proportion of a herd of cattle exhibits hypersalivation and hyperthermia. The back is slightly arched and knuckling of a hind pastern may be an initial sign. There is progressive lameness, anorexia, depression, and later, dry gangrene of the distal limbs (hind limbs first). Signs usually develop within 10–21 days after turnout into a fescue-contaminated pasture in fall. A period of frost tends to increase the incidence.”
Coffey said the disease is very unpredictable because if conditions are right for grasses, they could also be right for toxins. Preventative measures can be taken to avoid the issue.
“I recommend holding off on winter grazing until after the first hard freeze,” Coffey said.
Smithers suggests keeping forages cut and rotating herds to help avoid fescue toxicosis. He said some helpful forage management practices for combating fescue toxicosis include:
• Replacing endophyte-infected tall fescue with low-endophyte tall fescue, endophyte-free tall fescue or other grass species for grazing or hay
• Diluting endophyte-infected tall fescue with other grasses or legumes
• Ammoniating fescue hay
• Increasing stocking rates on endophytic fescue pastures to prevent plant maturation and seedhead formation
Coffey said diluting toxic grasses with other types of forage can help with fescue toxicosis aversion. He also said providing mineral supplements is certainly important and producers need to use a good quality mineral because the toxins cause the depletion of copper.
“If clinical signs of dry gangrene in the distal extremities are being realized by the producer then it is unlikely to salvage the situation,” Smithers said.
Fescue foot affects a herd in many ways, some cows may lose their extremities, calving rates can be negatively impacted and there can be reduced growth in calves.
“Cattle performance is generally dependent on two primary factors: the production environment and the genetic composition of the animal,” Smithers said. “Tall fescue, as a forage widely used to provide nutrients to a large number of cattle, is a major environmental component of many beef production systems. Cattle managers can address this economically significant problem by altering the environmental input through forage management.”
